synopsys: Fix odd/even frame handling for ISO
synopsys: Fix odd/even frame handling for ISO

Current implementation always sets odd/even bit for ISO transactions.
This is a good strategy only if interval is 1.
For ISO endpoint interval in (micro)frames is computed as
2^(interval-1), which means that odd/frame number should stay
same for interval values > 1.
With this change only when interval is 1 odd/even bit is modified.

hathach/tinyusb,hathach/tinyusb,hathach/tinyusb